title: Is a methyl group always hydrophobic? Hydrophilicity of trimethylamine-N-oxide, tetramethyl urea and tetramethylammonium ion.
abstract: We have developed what we call the 1-propanol(1P) probing methodology. By using it, we determined the relative hydrophobicity/hydrophilicity indices of 2-butoxyethanol, a typical hydrophobe; urea, a typical hydrophile; and trimethylamine-N-oxide, an amphiphile. By comparing these indices with those for other solutes studied earlier, including tetramethyl urea, tetramethylammonium ion, mono-ols, and polyols, we suggest that methyl groups attached to an N atom, or N-methyl groups, do not promote hydrophobicity but, rather, enhance hydrophilicity.
authors.affiliation: Department of Chemistry, The University of British Columbia, Vancouver, BC, Canada. koga@chem.ubc.ca
authors.forename: Yoshikata
authors.initials: Y
authors.lastname: Koga
authors.forename: Peter
authors.initials: P
authors.lastname: Westh
authors.forename: Keiko
authors.initials: K
authors.lastname: Nishikawa
authors.forename: S
authors.initials: S
authors.lastname: Subramanian
mesh_terms: D000433:1-Propanol / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D008744:Methylamines / Q000737:chemistry*; D008782:Methylurea Compounds / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D008744:Methylamines; D008782:Methylurea Compounds; D000644:Quaternary Ammonium Compounds; D014867:Water; C004168:1,1,3,3-tetramethylurea; D000433:1-Propanol; C005855:trimethyloxamine; C027917:tetramethylammonium